They're completely new to me - perhaps they deserve their own thread.
I can't see any problem if they are used in conjunction with normal text - which they can't in fairness replace because not everyone owns a smart phone. Could you clarify - is a mobile phone signal needed, because if it is they wouldn't work out at Silbury.

Huh, I've never had any signal probs at Silbury, must be different providers...

The idea is to enhance the site, provide access to TMA, the HER/SMR, Meg Portal etc from an easily scanable point on site. The normal signage would remain on site.

I admit I've never tried to phone anyone from Silbury, however, in many of the locations around Avebury my mobile doesn't receive a signal ... which is just fine by me.

Thanks for the info, have also read the other posts on this subject - looks like an interesting development.